1. Technical Field
The present invention relates to a packet processing apparatus and method. More particularly, the present invention relates to a packet processing apparatus and method in an ethernet switch system which provides layer 2/3 switch functions based on an ethernet switch chip. The packet processing apparatus and method of the invention, even if overloaded with packets, can actively update Internet Protocol/Media Access Control (IP/MAC) address information of a next hop necessary for ethernet switch chip-based Internet Protocol (IP) switching in order to transmit the packets to destination hosts.
2. Description of the Related Art
In general, an Internet Protocol (IP) address and a Media Access Control (MAC) address of source and destination hosts are inevitably necessary in order to use an ethernet switching-based layer 3 switch (IP routing) function in a layer 2 (based on MAC) and layer 3 (based on IP) switching apparatus based on an ethernet switch chip.
In order to update IP address and MAC address information of a destination host, the ethernet switch chip traps a packet, even if it is headed for an IP address not existing in the layer 3, and this causes the following problems.
First, since packet trapping by the ethernet switch chip continues until a corresponding layer 3 table is updated, the central processing unit (CPU) will be overloaded with packets to the extent that it cannot transmit Address Resolution Protocol (ARP) packets. This may become worse if the ethernet switch chip has a larger bandwidth.
Second, if a packet received from a source host is headed for an IP address that does not exist in the layer 3 table, the CPU will repeatedly transmit ARP packets to a destination host. This will cause a problem of CPU overload and will waste network bandwidth.
Third, as layer 3 table update based on ARP has the above-mentioned problems, when an innocent packet headed for a wide IP bandwidth is received with priority to other packets, the CPU successively generates a large amount of ARP packets. This results in CPU overload and waste in network bandwidth while endangering network security.
In order to operate ARP by means of the CPU, only one packet per corresponding IP address should be trapped to the CPU. However, the ethernet switch chip does not support such a function, and thus a measure to trap packets as little as possible to the CPU is still required.